Electromagnetic switching mechanism



July 30, 1963 A. J. GRENIER 3,099,725

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July 30, 1963 A. J. GRENlE 3,09 5- ELECTROMAGNETIC SWITCHING MECHANISM Filed May 27. 1960 5 Sheets- Sheet 2 A in: e If. Grenz'en Azf July 30, 1963 A. J. GRENIER ELECTROMAGNETIC SWITCHING MECHANISM Filed May 27, 1960 5 Sheets-Sheet 5 [n ventor, a I o A z m e :1? G'r'enzer,

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July 30, 1963 A. J. GRENIER 3,099,725

ELECTROMAGNETIC SWITCHING MECHANISM Filed May 2'7, 1960 5 Sheets-Sheet 5 Inventor, Aim e J. G'rerzier,

United States Patent Office Patented July 30, 1963.

3,099,725 ELECTROMAGNETIC SWITCHING MECHANISM Airn J. Grenier, North Attleboro, Mass., assign-or to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed May 27, 1960, Ser. No. 32,176 18 Claims. (Cl. 20087) This invention relates to new and improved electrical switch structures, and more particularly, to a new and improved relay.

One object of this invention is the provision of such a switch structure, the component parts of which can be rapidly and easily assembled into and retained in operative condition.

Another object of the instant invention is the provision of a new and improved plunger-armature type subassembly which affords added weight to provide increased contact pressure and contact weld breaking force on drop out without necessitating a deleterious or undesirable alteration of the magnetic relationships between the armature and the coil in the magnetic circuit.

A further object of this invention is the provision of a new and improved relay which affords increased contact pressure, minimizes contact bounce, vibration and arcing.

Among the further objects of the invention are included the provisions of a relay which is compact, simple in design, versatile and susceptible to operation over a wide range of current values, efiicient, low cost and easily manufactured and assembled into final operative condition.

Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of the various possible embodiments of the invention is illustrated:

FIG. 1 is a top plan view of an electrical switch embodying the present invention;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a view taken on line 3--3 of FIG. 2, with the cover removed for clarity of illustration;

FIG. 4 is a top plan view of a cover member for the switch shown in FIG. 1;

FIG. 5 is a front elevational view of the cover member shown in FIG. 4;

FIG. 6 is a bottom plan view of the cover;

FIG. 7 is a sectional view taken on line 77 of FIG. 2, showing certain parts in dashed lines and in exploded position; 7

FIG. 8 is a sectional view taken on line 88 of FIG. 2, showing certain parts in dashed lines in exploded relation;

FIG. 9 is a sectional view taken on line 9-9 of FIG. 1;

FIG. 10 is a view similar to FIG. 9, showing the bridging element and plunger subassembly in contacts closed position; and

FIG. 11 is an exploded perspective view of the electrical switch shown in FIG. 1.

Referring now to FIG. 1, an electrical switc'h embodying the instant invention is illustrated as being .generally indicated by the reference number 20. Switch 20 takes the form of an electromagnetic relay and includes a casing member 22 and a cover member generally referred to by numeral 24, and best shown in FIGS. 4-6. Casing member 22 includes beveled lands or projections 25 and 26, and cover member 24 includes a boss or projection 27.

Projections 25, 26 and 27 are adapted to interfit and mate with a spring-type bracket which, when in operative position about the respective projections, will secure and maintain the cover member and casing, and the parts contained thereby, in fixed, operative position. Such a bracket (not shown) is fully described and claimed in my copending application, Serial No. 782,261, filed December 22, 1958, now abandoned and in a co-pending continuation-impart application thereof, Serial No. 53,586, filed August 26, 1960, which matured as US. Patent No. 3,061,258 on October 30, 1962, which disclosure is incorporated herein by reference.

Switch 20 includes a pair of stationary contacts 30 and 32 carried respectively by terminals 34 and 36, each of the latter being formed of a suitably electrically conductive material. Switch 20 also includes a third electrically conductive terminal 38, formed of a suitably electrically conductive material. Each of terminals 34, 36 and 38 are slidably received within, and respectively interfit with open-ended guideway apertures 40, 42 and 44 provided in casing member 22, (as best shown in FIGS. 3 and 11). Each of apertures 40, 42 and 44 respectively include a pair of upstanding walls 45, 46; and 48, 50; 49, 51 which interfit with respectively adjacent side portions of terminals 34, 36 and 38. Upstanding walls 45, 46; 48, 50 and 49, 51, each respectively include sidewall projections 52, 54; 56, 58 and 57, 59 which extend inwardly of casing 22 and respectively guide terminals 34, 36 and 38 for slidable insertion thereof into casing 22. Each of sidewall projections 52, 54; 56, 58 and 57, 59 also include inwardly projecting and opposed boss or shoulder portions 60, 62; 64, 68 and 65. Terminals 34, 36 and 38 are respectively supported on bosses 60, 62; 64, 68 and 65 and are maintained in spaced relation with respect to interior surface 69 of casing 22, as best seen in FIGS. 7 and 9. As best seen in FIGS. 3 and 11, each of apertured guide- Ways 40, 42 and 44 include pairs of recessed corner portions 70, which mate and interfit with pairs of projections 72 respectively provided on each of terminals 34, 36 and 38 to limit the extent of inward insertion thereof into casing 22.

Each of terminals 34, 36 and 38 are also respectively provided with an aperture 73, 74 and 76, within which projections 78, and 82 are respectively disposed. Pro.- je'cti ons 78, 80 and 82 are fixedly carried by cover member 24 and extend through the respective apertures 73, 74 and 76 to facilitate alignment of the respective terminals and casing member, maintain these parts in fixed, assembled relation, and prevent longitudinal movement of the respective terminals within their respective apertured guideways. sidewalls 45, 46; 48, 50 and 49, 51 and their respective sidewall and shoulder projections, oo-o perate with the respective adjacent side portions of terminals 34, 36 and 38, to prevent rotation of these terminals about the axis of their respective interfitting projections 78, 80 and 82. Casing member 22 provides a recess in the form of a socket 84, as best seen in FIG. 8, which interfits with projection 82 carried by cover member 24, and oo-operates therewith to align 'and maintain cover member 24 and casing 22 in fixed vassembled relation.

Referring rrow to FIGS. 4-6, cover member 24 includes a plurality of upstanding projections and 92 which respectively support projections 78 and 80. Projections 90 and 92 are respectively slidably received between pairs of upstanding opposed walls 94, 96 and 98, 100, provided by casing 22, 'as best seen in FIGS. 3 and 9. Cover member 24 further includes a plurality of transversely extending spaced shoulder portions 102, 104, 106, 108 and 110, which interfit with and rest on complementary shaped reicess portions provided in casing 22, so as to facilitate alignment of and maintain the cover member 24 and casing 22 in relatively fixed, assembled relation. It is to be noted that cover member 24, because of the various projections, i.e. 78, 80, 82, 90 land 92, and the plurality of spaced shoulder portions advantageously preclude inadvertent misorientation of the cover member and casing.

Casing 22 is provided with a cylindrical bore or cavity 112, which is adapted to receive an armature and a nonmagnetic slug or Weight of a plunger sub-assembly designated generally by numeral 120 for reciprocal sliding movement therein. The plunger subassembly thus includes a two part plunger, one part comprising a magnetic armature and the other part comprising a non-magnetic slug or weight, as will be described in greater detail below.

As best seen in FIGS. 9-11, the plunger subassembly 120 comprises a cylindrical plunger weight or armature 122 formed of a suitable magnetic material, such as, for example, SAE 1113 steel. Formed integrally with armature plunger 122 is a shank 124 of considerably reduced diameter. Shank 124 is provided with a beveled reduced diameter portion 126 at its free end, and includes a '6- cessed annularly extending shoulder portion 128. An apertured movable bridging contact member 130 is slidably mounted on shank portion 124. Bridging contact member 130 includes a main body portion 132 and a pair of spaced contact arms 134 and 136. Fixedly mounted and electrically connected to each of contact arms 134 and 136 is a pair of electrical contacts 140 and 142 which are adapted to respectively mate with stationary contacts 30 and 32. Bridging member 130 is preferably formed of a high electrical conductivity material, such as a beryllium copper alloy. Selection of \a high conductivity material permits forming the bridging contact member of a very thin gauge material, thereby maintaining the weight of the bridging member at a minimum. Thus the major portion of the weight of the plunger subassembly can operate to break apart contact welds.

Contact arms 134 and 136 lie in a plane oifset from the plane of the main body portion 132 of the element, as best seen in FIGS. 9, and 11. Flexible upstanding portions 146 and 148, which interconnect the contact arms 136 and 134 respectively with the main body portion, are adapted to flex. The flexible nature of connecting portions 146 and 148 and the inherently resilient nature of the bridging element, advantageously increases the tendency for contact wiping to clean the respective pairs of contacts 30, 140 and 32, 142 upon contact closing. v Further, the offset nature of the contact arms tends to isolate each of the pairs of contacts 30, 140 and 32, 142 into separate compartments formed, for example, respectively by walls 94, 96 and 98, 100 of casing 22 on each of opposite sides .of the plunger receiving Well or hollow portion 112. Isolating the relative pairs on": contacts is advantageous for are shadow purposes in preventing the formation of a low resistance current path which might be formed by splatter or particles thrown off from the contacts, or by deterioration of other parts due to arcing, etc., in a manner well known. Contact arms 134 and 136, by being of reduced width (see FIG. 3) advantageously avoid physical contact with the side walls of the interior portion of casing 22, thus providing arc shadow and minimizing the formation of a low resistance current short circuiting path and minimizing the possibility of undesirable changes in calibration. Bridging contact member 130 provides an aperture 150, as best seen in FIG. 9, within which shank portion 124 is loosely disposed.

Circumferentially disposed about shank portion 124 is a spring member 154 located intermediate the bridging member 130 and the annularly extending shoulder portion 128 adjacent the free end of shank 124. Spring 1'54 urges bridging member 130 upwardly, as best seen in FIG. 9, into engagement with the lower surface 156 (see FIG. 10) of armature 122 and in a contacts-closing direction. One end 158 of spring 154 engages the underside of bridging member 1'30 and the opposite end 160 of reduced diameter engages shoulder portion 128 of shank 124, as best seen in FIGS. 9-11. Spring 154 is preferably of the type which has a variable spring rate, i.e. the force required for compression varies with the compressive or deflective state of the spring. It is intended that the term variable rate spring include those types of springs with which the force required for unit deflection of the spring increases with increased deflection or compression of the spring. The variable rate spring advantageously permits operation of the relay over a wide range of current values. By comparison, when a spring at a given uniform spring rate is employed, the relay may, for example, operate satisfactorily at a low operating current value. However, at a higher current value, unsatisfactory performance might be encountered because of such undesirable effects as high contact bounce, chatter, etc. which would be experienced at this higher operating current value. These undesirable effects are advantageously obviated, or at least minimized, by the plunger subassembly of the instant invention. "Further, the unique construction of the plunger subassembly thus far described, advantageously facilitates rapid subassemlbly. 'All that is necessary to provide the plunger subassembly 120 is to slidably place the bridging contact member about stem portion .124 and to slidably insert spring 154 which quickly snaps into place with portion 1 60 abutting shoulder portion 128.

The unique plunger subassembly of the instant invention further includes a separate weight or slug 162, as best seen in FIGS. 9-1 l, for a purpose to be described below. Slug or weight 162 may be formed of a diameter corresponding to that of armature or plunger 122 and may be formed of a non-magnetic material such as, for example, silicon bronze, brass, stainless steel, etc.

Referring now to FIGS. 9 and 10', slug 162 and plunger or armature 122 are slidably received in the cylindrical cavity 112 provided by casing 22 as shown. Casing 22 further includes an external cylindrical portion 168 and a flange 170, which provides a spool for an energizing coil 172. Disposed about cylindrical portion 168 is a plurality of mutually insulated turns of electrically conductive wire forming a coil 172. As best seen in FIG. 2, one end of coil 1172 is electrically connected to terminal 34 and the other end is electrically connected to terminal 38. Cylindrical spool portion 168 serves a dual function of providing a spool for energizing coil 172 and also providing a housing and guide for armature 1-22 and slug or weight 162, and obviates the necessity for other intricate and complex guiding members for the one-piece armature and stem. Such features as nylon bushings and stem guides which are ordinarily or conventionally required for proper guidance of the reciproeating armature are advantageously eliminated by the arrangement of the instant invention.

When coil 172 is electrically energized, magnetic armature 122 will be moved upwardly in the direction of the arrow, as shown in FIG. 10, to close the contacts 140, 30 and 142, 3 2. Upon energization of coil 172, and upward movement of armature portion 122, non-magnetic slug 162 will also be moved upwardly in the direction of the arrow, as shown in FIG. 10. Non-magnetic slug 162 uniquely and advantageously adds weight to the plunger subassembly so as to increase contact pressure respectively between contacts 30, 140 and 32, 142. The increase in weight aflorded by the non-magnetic slug 162 necessitates a greater number of ampere turns to lift the armature and the additional weight, and thereby also effectively increases the contact pressures. Added weight 162 is cfurther advantageous in facilitating drop-out or opening of contacts, and provides a greater force for breaking welds which may (have formed between the respective pairs of contacts.

Upon energization of coil 172, armature 122 and weight 162 will move in the direction of the arrow from the contacts-open position shown in FIG. 9, to the contacts-closed position shown in FIG. 10. As the bridging element moves upwardly sufliciently so that contacts 140-, 30 and 142, 32 mate, movement of the arm-ature 122 and the bridging element 130 will be momentarily or partially arrested. However, weight or slug 162 because of its momentum, will continue to move upwardly relative to the armature 122, as shown in the dashed line portions in FIGS. 9 and 10 As the weight 162 momentarily leaves armature 122 thus temporarily relieving the armature 122 from the burden of supporting this weight, armature 122 will then again move upwardly under a temporarily increased net upward force on the armature. This temporary increased upward force on the armature (i.e. before the weight or slug 162 returns downwardly to be again supported by the armature 122) advantageously increases contact pressure or contact sealing pressure at the time of contact making, and thereby mlinimizes contact resistance, heat generation, and the tendency of contact welding.

Further, the fact that the weight or slug 162 temporarily separates from the armature .122 by its continued movement upon contact making advantageously tends to stabilize the plunger subassembly to reduce vibration and also to minimize contact bounce. Non-magnetic slug or weight 162, after leaving armature 122, will continue to move upwardly and strike the surface 180 at the upper extremity of cavity 112 (see FIG. 1O). Thereafter, it will move downwardly into supporting engagement with armature 122. Thus, slug 162- uniquely dissipates at least part of the kinetic energy or momentum developed by the plunger subassembly in moving from a contactsopen to a contacts-closed position, at least a part of which is absorbed by the casing when the slug 162 strikes surface 189. This partial energy dissipation advantageously obviates or at least minimizes contact chatter and bounce and also vibration to which the plunger subassembly is subjected.

The non-magnetic slug :162, in affording the unique and unexpected results mentioned above, advantageously does not necessitate an increase in relay dimensions or require any deleterious alteration in the magnetic circuit or of magnetic relationships between the armature 124 and the energizing coil 172. The height of the relay is maintained at a minimum without affecting the magnetic circuit of the relay.

Cover member 24, as best seen in FIGS. 4, 8, 9, 10 and 1 1, includes a cylindrical hollow cavity 190 which receives the lower stern portion 124 and spring 154 of plunger subassembly 120 for reciprocal sliding movement therein. Adjacent the outer portion of cyilndrical cavity 190 are a pair of spaced projecting abutments 192 and 194 which are adapted to engage the underside of the main body portion 132 of bridging element .130 to support the latter in the contacts-open position, as best seen in FIG. 9. Cover member 24 further includes a pair of spaced deep recesses or pockets 196 and 198 for the purpose of receiving debris and matter such as contact splatter or casing material which is broken down during arcing or other debris which might form a low-resistance current path. Casing member 22 is further provided with a plurality of projecting ribs 200 having recessed portions therebet-ween which are adapted to collect debris and other matter such as that mentioned above. Projecting ribs are thus effective for are shadow to prevent the undesirable formation of a low-resistance current path which might be formed by such debris. Cylindrical cavity 112 is: likewise provided with a plurality of axially extending circumferentially spaced rib projections 202. Rib projections 20 2, in addition to advantageously obviating the formation of a low resistance current path, also provides line contact for engagement with slug 162 and armature 122 thereby minimizing surface-to-surface contact. Projections 202 thus prevent or at least minimize binding or resistance to slidable reciprocating movement of the armature 122 and slug 162 within the cavity, which could be caused by debris in the cavity.

The electrical switch 20 thus far described advantageously permits mass production of a variety of subassemblies which may be quickly and easily assembled together in final adjusted position.

Referring now to FIG. 11, wherein the switch is illustrated in an exploded perspective view, it can be seen that to assemble the switch in operative conditions, it is only necessary to do the following:

(1) Slidably insert each of terminals 34-, 36 and 38 in their respective aperture guideways.

(2) Drop or place slug 162 into cavity 112.

(3) Place or drop armature 122 of the plunger subassembly (which is assembled in the manner described above, by slidably inserting bridging contact about stern 124 and slidably disposing spring 154- about stem 124 with end of spring 154 snapping in place about shoulder 128 on stem 124).

(4) Once the terminals, slug 162 and plunger subassembly 120 are all in place in casing 22, it is now merely necessary to insert cover member 24 into operative position, as shown in FIG. 9, whereby projections 78, 80 and 82 will interfit with their respective apertures in terminals 34, 36 and 38 to firmly secure them in place.

(5) It is then only necessary to apply a mounting bracket, such as the one described in the aforementioned copending application, to firmly secure the assembled apparatus and maintain the same in final assembled relation.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

It is to be understood that .the invention is not limited in its application to the details of construction and arrangement of par-ts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As many changes could be made in the above constructions Without departing from the scope of the invention, it is intended that all matter contained in the above de scription :or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense, and .it is also intended that the appended claims shall cover all such equivalent variations as come within the true spirit and scope of the invention.

I claim:

1. An electrical switch comprising a casing including first and second casing members, one of said casing members including stationary contact means therein; movable contact means engageable with said stationary contact means; a bridging contact plunger type subassembly comprising a magnetic armature; shank means integral with said armature; a bridging element supporting said movable contact means and slidably mounted on said shank means; said shank means including a shoulder portion and spring means interposed between said shoulder portion and said bridging element; one of said casing members providing a hollow cavity in which said bridging contact plunger subassembly is disposed and guided for reciprocating movement axially thereof; an energizing coil disposed exteriorly of said casing member-s for said armature, a non-magnetic weight member disposed in a portion of said hollow cavity adjacent said armature, said nonmagnetic weight member having a cross-sectional configuration corresponding to that of said portion of said hollow cavity, said weight member being movable with said armature in each of two opposite directions within said portion of said hollow cavity and also being movable relative to said arrnlature; the end of said hollow cavity closest said nonmagnetic weight member providing a stop to limit movement of said weight member relative to said armature.

2. An electrical switch comprising a casing including first and second casing members, one of said casing members including stationary contact means therein; movable contact means engageable with said stationary contact means; a bridging contact plunger type subassembly comprising a magnetic armature; shank means interconnected with said armature for movement therewith; a bridging element supporting said movable contact means and slidably mounted on said shank means; said shank means including a shoulder portion; spring means interposed between said shoulder portion and said bridging element; one of said casing members providing a hollow portion in which said bridging contact plunger subassembly is disposed and guided for reciprocating movement axially thereof; an energizing coil disposed exteriorly of said casing members for said armature; and non-magnetic means disposed in said hollow portion adjacent said armature, said non-magnetic means being movable with and also relative to said armature means and said switch including stop means for limiting movement of said non magnetic means relative to said armature.

3. The switch as set forth in claim 2 and wherein said spring means is disposed about said shank means and comprises a variable rate spring.

4. The switch as set forth in claim 3 and wherein said bridging element comprises a main body section which is slidably disposed about said shank means and includes .a pair of spaced contact arms each disposed in a plane oilset fromthe plane of said main body.

5. The switch as set forth in claim 4 and wherein said arms are offset from said main body portion in a direction toward said stationary contacts.

6. The switch as set forth in claim 2 and wherein said hollow portion is provided with longitudinally extending, substantially parallel spaced rib portions.

7. An electrical switch comprising a housing having a pair of spaced stationary contacts disposed therein; said housing further including a cylindrical hollow portion for reception of a cylindrical magnetic armature of a bridging contact plunger type subassembly; said magnetic armature of said bridging contact plunger type subassembly including a shank portion of lesser diameter interconnected with said armature; said shank portion being provided adjacent the free end thereof with shoulder means; an electrically conductive bridging element carrying a pair of spaced electrical contacts for engagement with said stationary contacts; said bridging element being slidably supported on said shank portion; spring means intermediate and engaging said bridging element and said shoulder portion on said shank means; said spring means comprising a variable rate type spring; a non-magnetic weight member formed separately from and supported on said magnetic armature in said cylindrical hollow portion for reciprocal sliding movement therein; said non-magnetic weight member being movable with and relative to said armature, the end of said hollow portion closest to said non-magnetic weight member providing a stop to limit movement of said weight member relative to said armature.

8. In an electrical switch, a bridging contact plungertype subassembly comprising a two-part plunger; at least one of said parts comprising a magnetic armature; stem means interconnected with said armature and including a spring retaining portion adjacent its free end thereof; a bridging element slidably mounted on said stem means intermediate said free end and said magnetic armature; said bridging element supporting a pair of spaced electrical contacts; spring means intermediate said bridging element and said spring retaining portion urging said bridging element for engagement with said magnetic armature; said other part of said plunger assembly comprising a non-magnetic weight member formed separately from and supported by said armature for unrestricted movement therewith as a unit in a first direction; said weight member also being positioned for movement with said magnetic armature in a second direction opposite to said first direction; said weight member further being movable relative to said armature after said armature and weight member have moved together a predetermined amount in said second direction; said switch including stop means for limiting movement of said weight member relative to said armature.

9. The subassembly as set forth in claim 8 and wherein said bridging element comprises a central body portion and a pair of spaced contact-carrying arms; each of said arms being located adjacent a respective end of said central portion and said contact arms lying in a plane offset from said central portion; and flexible means integral with and interconnecting said central portion and each of said contact arms.

10. In combination; a casing member; said casing member being provided with a pair of spaced open-ended guideway apertures; a pair of terminals each received in a respective one of said apertures; each of said terminals providing an aperture adjacent one free end thereof; each of said terminals further including an electrical contact adjacent said aperture-s; a bridging contact plunger type subassembly comprising a two-part plunger; one of said parts comprising a magnetic armature; and the other of said parts comprising a non-magnetic weight member supported by said magnetic armature; shank means integral with said armature; a bridging element supporting movable contact means for engagement respectively with each of said first-named contacts; said bridging element being slidably mounted on said shank means; said shank means including a shoulder portion adjacent one free end thereof; and spring means interposed between said shoulder portion and said bridging element, urging the latter tor movement in a contacts-closing direction; said casing providing an elongated cavity in which said two-part plunger is disposed for reciprocating movement axially thereof; an energizing coil disposed exteriorly of said casing for said armature; said non-magnetic member being movable with and also relative to said armature on actuation thereof by said energizing coil; a cover member for said casing; said cover member including a pair of projections, each of which are received within a respective one of said apertures in said terminals to align and maintain said terminals in fixed assembled relation.

11. The electrical switch as set forth in claim 10 and wherein said cavity and said two-part plunger are cylindrical in shape, and said cavity includes a plurality of longitudinally extending and substantially parallel, spaced ribbed portions.

12. An electrical switch comprising a housing having a pair of spaced stationary contacts disposed therein; said housing further including a cylindrical hollow portion for reception of a cylindrical magnetic armature of a bridging contact plunger type subassembly; said magnetic armature of said bridging contact plunger type subassembly including a shank portion of lesser diameter integral with said armature; said shank portion being provided adjacent the free end thereof with shoulder means; an electrically conductive bridging element carrying a pair of spaced electrical contacts for engagement with said stationary contacts; said bridging element being slidably supported on said shank portion; spring means intermediate and engaging said bridging element and said shoulder portion on said shank means; a non-magnetic weight member supported by said armature in said cylindrical hollow portion for reciprocal sliding movement therein; said non-magnetic member being positioned for continuous movement with said armature in said hollow portion when said armature moves in a first direction, said non-magnetic member also being positioned for movement with and relative to said armature in said hollow portion when said armature moves in a direction opposite to said first direction.

13. In an electrical switch, a bridging contact plungertype subassembly comprising a two-part plunger; at least one of said parts comprising a magnetic armature; stem means interconnected with said armature; a bridging element mounted on said stem means; said bridging element supporting a pair of spaced electrical contacts; said other part of said plunger assembly comprising a non-magnetic Weight member formed separately from and supported by said armature for unrestricted movement therewith as a unit in a first direction; said weight member also being positioned for movement with said magnetic armature in a second direction opposite to said first direction; said weight member further being movable relative to said armature after said armature and weight member have moved together a predetermined amount in said second direction; and said switch including stop means for limiting movement of said weight member relative to said armature.

14. An electrical switch comprising a housing having a pair of spaced stationary electrical contacts disposed therein; said housing further including a cylindrical hollow portion for reception of a cylindrical magnetic annature of a bridging contact plunger-type subassembly; said magnetic armature of said bridging contact plungertype subassembly including a shank portion of lesser diameter interconnected with said armature; an electrically conductive bridging member carrying a pair of spaced electrical contacts positioned for engagement with said stationary contacts; said bridging member being carried by said shank portion; a non-magnetic weight member formed separately from and supported on said magnetic armature in said cylindrical hollow portion for reciprocal sliding movement therein, said non-magnetic weight member being movable with and relative to said armature, the end of said hollow portion closest to said nonmagnetic weight member providing a stop to limit movement of said weight member relative to said armature.

15. An electrical switch comprising a casing including first and second casing members, one of said casing members including stationary contact means therein; movable contact means engageable with said stationary contact means; a bridging contact plunger-type subassembly comprising a magnetic armature; shank means interconnected with said armature; a bridging element supporting said movable contact means and slidably mounted on said shank means; one of said casing members providing a hollow cavity in which said bridging contact plunger subassembly is disposed and guided for reciprocating movement axially thereof; an energizing coil disposed exteriorly of said hollow cavity for said armature; a non-magnetic weight member disposed in a portion of said hollow cavity adjacent said armature, said weight member being formed separately from and supported on said armature for movement therewith within said portion of said hollow cavity, said weight member also being positioned for movement relative to said armature within said portion of said cavity, said weight member having a cross-sectional configuration which is complementary in shape to the cross sectional configuration of said portion of said cavity, the end of said cavity closest to said weight member providing a stop to limit movement of said weight member relative to said armature.

16. An electrical switch comprising a housing having stationary electrical contact means disposed therein; said switch further including an elongated magnetic armature; said switch including means for guiding said magnetic armature for reciprocal movement in said housing; said magnetic armature being interconnected with movable contact means for movement of the latter into and out of engagement with said stationary contact means; a non-magnetic weight member formed separately from and supported on said magnetic armature for movement therewith, said non-magnetic weight member also being movable relative to said armature, said switch further including electromagnetic means for causing movement of said magnetic armature, and said switch including stop means for limiting movement of said non-magnetic Weight member relative to said armature.

17. An electrical switch comprising a housing having a pair of spaced stationary electrical contacts mounted therein, said switch further including an elongated magnetic armature and means for guiding said armature for reciprocal movement in said housing; a bridging member comprising a central body portion and a pair of spaced contact-carrying arms; each of said arms being located adjacent a respective end of said central body portion and lying in a plane offset from the plane of said central body portion; flexible means integral with and interconnecting said central body portion and each of said contact-carrying arms; each of said contact-carrying arms mounting a respective one of a pair of movable contacts positioned for engagement with said stationary contacts; said magnetic armature being interconnected with said central body portion of said bridging member for movement of the latter and the movable contacts carried thereby in a direction to cause closing of said stationary and movable contacts whereby upon closing of said contacts, said offset contact arms are flexible relative to said central portion to effect a contact wiping action; a non-magnetic weight member formed separately from and supported on said magnetic armature for movement therewith, said non-magnetic weight member also being movable relative to said armature, said switch further including electromagnetic means for causing movement of said magnetic armature, and said switch including stop means for limiting movement of said non-magnetic weight member relative to said armature.

18. An electrical switch comprising a casing including first and second casing members, one of said casing members including stationary contact means therein; movable contact means engageable With said stationary contact means; a bridging contact plunger-type subassembly comprising a magnetic armature; shank means interconnected with said armature; a bridging element supporting said movable contact means and mounted on said shank means; one of said casing members providing a hollow cavity in which said bridging contact plunger subassembly is disposed and guided for reciprocating movement axially thereof; said switch including an energizing coil for said armature; a non-magnetic weight member disposed in a portion of said hollow cavity adjacent said armature, said weight member being formed separately from and supported on said armature for movement therewith within said portion of said hollow cavity, said weight member also being positioned for movement relative to said armature within said portion of said cavity, and the end of said cavity closest to said weight member providing a stop to limit movement of said weight member relative to said armature.

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16. AN ELECTRICAL SWITCH COMPRISING A HOUSING HAVING STATIONARY ELECTRICAL CONTACT MEANS DISPOSED THEREIN; SAID SWITCH FURTHER INCLUDING AN ELONGATED MAGNETIC ARMATURE; SAID SWITCH INCLUDING MEANS FOR GUIDING SAID MAGNETIC ARMATURE FOR RECIPROCAL MOVEMENT IN SAID HOUSING; SAID MAGNETIC ARMATURE BEING INTERCONNECTED WITH MOVABLE CONTACT MEANS FOR MOVEMENT OF THE LATTER INTO AND OUT OF ENGAGEMENT WITH SAID STATIONARY CONTACT MEANS; A NON-MAGNETIC WEIGHT MEMBER FORMED SEPARATELY FROM AND SUPPORTED ON SAID MAGNETIC ARMATURE FOR MOVEMENT THEREWITH, SAID NON-MAGNETIC ARMATURE FOR MOVEMENT MOVABLE RELATIVE TO SAID ARMATURE, SAID SWITCH FURTHER INCLUDING ELECTROMAGNETIC MEANS FOR CAUSING MOVEMENT OF SAID MAGNETIC ARMATURE, AND SAID SWITCH INCLUDING STOP MEANS FOR LIMITING MOVEMENT OF SAID NON-MAGNETIC WEIGHT MEMBER RELATIVE TO SAID ARMATURE. 